Marine transportation of liquified gases

ABSTRACT

A ship of simplified construction for the marine transportation of liquefied gases at cryogenic temperatures is equipped with at least one concrete tank. In a first embodiment, the concrete tank is surrounded by a layer of sand. A second embodiment contemplates both a layer of sand surrounding the concrete tank and a further layer of insulating material within the tank. In a third embodiment, a layer of insulating material is provided within the concrete tank. A fourth embodiment of the invention relates to a concrete tank surrounded by a layer of insulating material which abuts the hull of the ship. And in a fifth embodiment of the invention, the entire hull of the ship is concrete and forms at least one containment tank. In the fifth embodiment, there may be provided a layer of insulating material within each tank.

United States Patent [72] Inventors Joseph J. Cuneo Scarsdale; Norman K.Basile. Hauppauge; George R. Knight; Thomas F. Bridges, Port Washington,N.Y.

[2]] Appl. No. 813.087

[22] Filed Apr. 3, 1969 [45] Patented Mar. 2, 1971 [73] Assignee John J.McMullen Associates, Inc. New York, N.Y.

[541 MARINE TRANSPORTATION 0F LIQUEFIED GASES 12 Claims, 3 Drawing Figs.[52] [1.8. CI. 114/74, 220/9 [51] Int.Cl 1363b 25/08, 865d 25/18 [50]Field of Search 114/74, 74

(A); 220/9,9(Al), l5

[56] References Cited UNITED STATES PATENTS 3,l36,l35 6/1964 Rigby etall'l4/74X(A) 3,457,890 7/1969 Rivas et al. l l4/74( A) PrimaryExaminer-Trygve M. Blix Attorney-Fleit, Gipple & Jacobson ABSTRACT: Aship of simplified construction for the marine transportation ofliquefied gases at cryogenic temperatures is equipped with at least oneconcrete tank. in a first embodiment, the concrete tank is surrounded bya layer of sand. A second embodiment contemplates both a layer of sandsurrounding the concrete tank and a further layer of insulating materialwithin the tank. In a third embodiment, a layer of in-' sulatingmaterial is provided within the concrete tank. A fourth embodiment ofthe invention relates to a concrete tank surrounded by a layer ofinsulating material which abuts the hull of the ship. And in a fifthembodiment of the invention,

the entire hull of the ship is concrete and forms at least onecontainment tank. In the fifth embodiment, there may be provided a layerof insulating material within each tankl PATENIEUMAR 219m 3566;824

' SHEET 1 [IF 3 INVENTORS JOSEPH J. CUNEO NORMAN K. BASILE GEORGE R.KNIGHT THOMAS E BRIDGES FIG. 1

PATENTEDHAR 21911 SHEET 2 BF 3 WW II WV INVENTORS JOSEPH J. CUNEO NORMANK. BASILE GEORGE R. KNIGHT BY THOMAS F BRIDGES TTORNIzYS Pmmsnm 2m:3.5651824 SHEET 3 BF 3 INVENTORS JOSEPH J. CUNEO NORMANK. BASILE GEORGER. KNIGHT BY THOMAS E BRIDGES 'TTORNEYS WWW in the field of transportingliquefied materials at cryogenic temperatures (of the order of -250 F.),many problems present themselves. it is well known that carbon steel,used extensively in ship building, is relatively weak at cryogenictemperatures. Therefore, the transportation of cryogenic material mustbe done in such a manner that the carbon steel hull of the ship isprotected from the low-temperature material transported thereby.

in the past, tanks having double barrier construction have beenpositioned within the hull of the ship and have been used to transportcryogenic material. These-tanks have necessarily been made of materialsother than carbon steel in view of the strength properties of this steelat low temperatures. Specifically, these tanks have been designed ofnickel-steel or aluminum alloys and have served, quite effectively, forcargo containment and for protecting the hull of the associated shipfrom exposure to extremely low temperatures. The double barrierconstruction is employed so that if the inner barrier should fail, dueto faulty welds, overstress or other causes, there remains a secondbarrier to contain the cargo and prevent exposure of the ship's bull tothe extremely low-temperature material housed in the container.

While the double barrier nickel-steel or aluminum alloy tanks have beenquite satisfactorily employed in the past, there are certaindisadvantages which are associated therewith. Particularly, a majordisadvantage is that materials of the nickel-steel and aluminum alloyvarieties tend to be quite costly. Further, the double barrier tanktends to be somewhat complex in its construction and also tends to beadversely affected by thermal stress caused by nonuniform coolingthereof. And still further, while it is thought to be improbahie, it isalways possible that both of the walls of the double barrierconstruction would fail, thereby exposing the hull of the vessel to thecryogenic temperature of the transported material.

SUMMARY OF THE lNVENTlON The present invention relates to the concept oftransporting cryogenic fluids, such as methane, nitrogen, oxygen, andthe like, at approximately saturation temperatures corresponding toatmospheric pressure within one or more steel reinforced concrete tankscontained within the hold of the ship. it is contemplated that largebulk quantities, up to approximately 50,000 tons, be transported. 7

By storing the cryogenic fluid in a concrete tank, many advantagesresult. Particularly, the concrete tank has excellent strengthproperties at cryogenic temperatures. Therefore, the problem involved inthe prior art, namely the concern with the container material becomingbrittle and weak at cryogenic temperatures, is avoided.

it is therefore one object of the invention to provide a chamber for thetransportation of cryogenic material, which chamber is extremely strongat cryogenic temperatures.

in view of the fact that the concrete tank exhibits superior strengthproperties, the construction of the ship may be simplified.

it is therefore another object of the present invention to provide aship which is relatively simple in construction and which effectivelyserves to transport cryogenic material.

While the concrete tank partially serves to insulate the cryogenictemperature of the transported material from the hull of the ship,additional insulation may be advantageous. It is therefore contemplatedthat an insulating space be provided between the concrete hull of theship and that this insulating space be filled with an insulatingmaterial such as dry sand. This arrangement forms the first embodimentof the present invention. To ensure that the cryogenic material housedwithin the concrete tank does not escape from said tank, it iscontemplated that there be provided a liquid and gas impervious liner onthe inner wall of the tank.

it is therefore a further object of the invention to provide a systemfor transporting a cryogenic material in an oceangoing vessel whichserves to safely house the material while efficiently isolating thecryogenic temperature associated with the material from the hull of theship. r

it should here be noted that the layer of dry sand serves additionalfunctions. The sand serves to support the concrete tank so that the tankis prevented from shifting within the hold of the ship. Also, the sandserves to minimize the structural requirements of the tank. By providinga layer of sand, the sand static head balances the static and dynamicforces associated with the cargo and serves to transmit these forces tothe structure of the ship.

it is therefore an additional object of the invention to provide asystem for transporting cryogenic material in an oceangoing vessel insuch a manner that the containment tank is fixed within the hold of theship and is not subjected to excessive static and dynamic forces formthe transported material.

While, in most instances, the invention as described above will proveadequate for insulating the hull of a ship from the cryogenictemperature of the material transported thereby, there are instances,such as those wherein the ambient temperature is extremely low, whereinfurther means may be provided for maintaining the hull of a ship atrelatively elevated temperatures. It is therefore contemplated by thepresent invention that there be formed a series of channels associatedwith the hull of the ship, channels which are conveniently formed bystiffener members, for conducting warm fluid therethrough. This fluidcan be of many types, such as hot water, oil, or antifreeze fluid.

lt is therefore a further object of the present invention to providepositive means for maintaining the hull of the ship at relativelyelevated temperatures.

There are instances wherein the cargo volume of a vessel fortransporting cryogenic material is an extremely important factor. it istherefore the desire to provide means for increasing the cargo volume ofsuch a vessel without necessitating an increase in the size of theassociated ship.

Along the lines of the preceding paragraph, it should be noted that onefunction of the sand layer intermediate the concrete container and thehull of the ship is to insulate the hull from cryogenic temperatures. itis therefore contemplated by the present invention that this sand layerbe reduced in width, or removed, and be supplemented by, or replaced byinsulating means having insulating properties superior to sand.

lt is well known that polyurethane is a better thermal insulator than issand. Therefore, a given width of polyurethane is more effective than acorresponding width of sand. By using polyurethane blocks as aninsulating medium, as a substitute for, or in addition to the sandlayer, the cargo volume of the fluid-containing vessel may be increased.

Therefore, in addition to the first embodiment of the invention, whereinthe concrete tank is surrounded by a layer of dry sand, additionalembodiments of the present invention are contemplated. These embodimentsemploy insulating systems of the foam block variety and are three innumber.

ln the second embodiment of the present invention, it is contemplatedthat a layer of dry sand be supplied between the concrete tank and thehull of the ship and also that a layer of insulating material such as,for example, a layer of polyurethane blocks, be provided on the innerwall of the concrete tank. in this manner, both the sand and thepolyurethane serve to insulate the hull of the ship from the cryogenictemperature associated with the transported material.

In the third embodiment of the present invention, the sand layer isentirely replaced by a series of polyurethane insulating blocks liningthe inner wall of the concrete tank. in this mode, it is necessary thatthere be provided a set of foundations for supporting the tank; while inthe first and second modes, the sand itself could perform thissupporting function.

in the fourth embodiment of the invention, the sand barrier is entirelyreplaced by a series of polyurethane insulating blocks, these blocks,rather than lining the inner wall of the tank, lining the hull of theship. Here again, foundation blocks are necessary to support the tank.

It should be noted that when the cryogenic material is separated fromthe concrete tank by an insulating layer, there is a reduction ofthermal stress in the walls of the concrete tank.

It should also be noted that while the exclusive use of polyurethaneblocks is extremely efficient, the exclusive use of sand is far lessexpensive. Therefore, an economic balance must be drawn between thehigh-insulating properties of polyurethane and the low-cost property ofsand. In this In this manner, the ratio of layer thicknesses may bedetermined.

It is therefore another object of the present invention to provide aconcrete tank for the transportation of cryogenic material, wherein saidtank is of maximum dimensions.

It is a further object of the invention to provide a concrete tank forthe transportation of cryogenic material, wherein said tank receives aminimum of stress from said cryogenic material.

In still a fifth embodiment of the present invention, it is contemplatedthat the entire hull of the ship be constructed of reinforced concrete.By so constructing a ship, the entire hull is of a material havingexcellent strength properties at cryogenic temperatures and the holdcontainment serves as a natural second barrier. Consequently, there isno need for sophisticated ship construction.

It is therefore still another object of the invention to provide a shipfor the marine transportation of cryogenic material, said ship being ofsimplified construction.

In accordance with the latter embodiment of this invention, it iscontemplated that the inner wall of the concrete hull, that forming thetank, may be provided with a set of polyurethane insulating blocks. Inthis manner, there is an insulation between the cryogenic material andthe concrete hull, and thus there is a reduction in the thermal stressexperienced by the hull.

It should be noted that in each of the above-noted embodiments of thepresent invention, it is contemplated that there be provided a gas andliquid impervious nonstructural liner positioned intermediate the tankand the cryogenic material. This liner may be made of any material whichis liquid and gastight at cryogenic temperatures and which remainsimpervious to the particular cargo being transported. An example of sucha material is polyethylene.

From the above, it is evident that the present invention solves many ofthe problems which plague the prior art. A concrete tank is used tohouse cryogenic material. This tank has properties making it extremelystrong at cryogenic temperatures, and consequently, the construction ofthe associated ship is substantially simplified.

The concrete tank is lined with a liner made of a material which is bothgastight and liquidtight at cryogenic temperatures. Thus, the linerforms a first barrier to the passage of the cryogenic material from thetank. The tank itself forms a temporary second barrier.

The invention further contemplates the use of an insulating systemformed of either sand or blocks of insulating material, or both.

In addition to the above, the present invention also contemplates anall-concrete ship. In this manner, cargo containment is extremelysafethe entire ship is of a material resistant to cold. Thus, many ofthe backup systems become unnecessary, and the construction of the shipis simplified.

The above-enumerated objects of the invention as well as many of theattendant advantages thereof will become more readily apparent whenreference is made to the following description taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a cross-sectional viewthrough the hull of a ship adapted for transporting cryogenic materialand constructed in accordance with the first embodiment of the present;

FIG. 2 is a cross-sectional view through the hull of a ship constructedin accordance with the present invention and serving to illustrateadditional embodiments of the invention; and

FIG. 3 is a cross-sectional view through a vessel constructed inaccordance with a further embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS With reference first to FIG. I,illustrating the first embodiment of the present invention, a ship fortransporting cryogenic material is shown generally at 10 and comprisesan outer hull 12 and an inner hull 14. Intermediate the two hulls l2 and14 are upper wing ballast tanks 16, side ballast tanks 18 and bottomballast tanks 20. The inner and outer hulls are connected andstructurally reinforced, both in the longitudinal and transversedirections, by conventional framing techniques.

Located within the inner hull l4, and spaced therefrom, is a reinforcedconcrete tank 22. The upper region of the concrete tank 22 is formed insuch a manner that the tank is inclined toward the centerline, or, putanother way, is in the shape of a bottleneck 24. It should be noted herethat numerous concrete tanks of varying dimensions may be employed in asingle ship; therefore, total container requirements can always be met.The tank 22 is provided with a series of pipes for filling and emptyingthe tank, for venting and for the performance of other conventionalfunctions.

The concrete tank forms a volume in which fluid at cryogenictemperatures may be housed. Forming a barrier between the inner wall ofthe tank 22 and the cryogenic material is a gas and liquid tightflexible liner 25 which may be, for example, of polyethylene.

The tank 22 is provided with two-chock systems. A conventional series ofchock pairs 26, 28 is distributed around the surface of the tank onfixed geometric centerlines to restrain the tank from longitudinal andtransverse movement while permitting the tank to expand and contractrelative to the structure of the ship about these fixed geometriccenterlines. If the space 34 is filled with sand, chock pairs 26, 28 areoptional because the sand will perform the same function. The secondchock system consists of conventional buoyancy chock pairs 30, 32. Thebuoyancy chocks are also optional.

Intermediate the concrete tank 22 and the inner hull I4 is a layer ofheavy material which may be, for example, dry sand. Sand has been foundwell suited to meet the needs of the present invention since it is aneffective support and insulator and since it is relatively inexpensive.

The functions of the sand are numerous. Particularly, the sand acts totransmit the static and dynamic forces of the cargo stored in theconcrete tank 22 to the structure of the ship 10. As a consequence, thetank design load may be minimized. Further, the sand functions as aninsulator serving to isolate the cryogenic temperature of thetransported material from the hull of the ship. Also, the thickness ofthe sand layer in the space 34 functions to regulate the boiloff rate ofthe material within the concrete tank. And finally, the sand in thespace 34 ensures that the tank 22 is held firmly in position relative tothe vessel 10.

It is quite common in ships to provide stiffeners for reinforcing thehulls thereof. These stiffeners can be designed so as to form channels,such as that indicated at 36, adjacent the inner hull 14. It iscontemplated by the present invention that channels 36 be used asconduits for fluid serving to heat the hull 14 at times when the ambienttemperature is relatively low. Such use of the channels 36 ensures thatthe steel hull 14 is maintained at a temperature above that near whichthe structure of the steel becomes weakened. Naturally, when the ambienttemperature is not dangerously low, the stiffener circulation systemwould remain idlc.

The tank 22 is sealed but for a plurality of pipes provided at its upperregion. These pipes serve many well-known functions, such as tankloading, tank unloading, venting, etc. It is contemplated that they beprovided in such a manner that the cryogenic liquid housed within thetank, the fully loaded level of which is shown at 42, be maintained at apredetermined pressure (usually between 1 and t p.s.i.g.).

It will be noted that the layer of sand covers the top of the tank 22.Thus, the cryogenic temperature of the transported material is insulatedfrom the external environment. It will also be noted that the sand whichcovers the tank 22 is itself covered by a hatch cover 40. This hatchcover is constructed in a well-known manner and is secured in place by aconventional gas and liquidtight expansion joint 41. To ensureinsulation between the external environment and the cryogenictemperature of the transported material, the pipes emergent from thetank 22 are insulated, in a well-known. manner, from the hatch cover 40.

In operation, the unloaded ship is prepared for loading by thecontrolled admission of cargo into the tank 22. The boiloff resultingfrom the. cool-down operation is removed from the tank 22 by means ofthe tank vent pipe.

At the conclusion of a voyage, the liquid housed in the concrete tank 22is removed. However, a small portion of liquid (between 2 percent and 6percent of the internal depth of the tank) is allowed to remain in thebottom of the tank 22 to maintain the tank in a cooled state. In orderto compensate for the loss of weight due to the removal of the cryogenicfluid, the ballast tanks 16;, 18 and 20 can be filled with water.

As noted above, a small portion of the cryogenic liquid is allowed toremain in the tank 22 after the tank has been unloaded. The reason forthis is twofold. First, the presence of liquid in the tank in a cooledcondition. Therefore, when the tank 22 is refilled, to begin a newvoyage, the problem of gasification, common when a warm tank is filledwith cryogenic fluid, is avoided. 'And second, if the liquid in the tankis methane, a sufficient amount thereof may be retained to permit theuse of the boilolf as a portion of the propulsion fuel for the vessel110.

As also noted above, the top of tank 22 is tapered. By so shaping thetank, the free surface area is reduced and thus the adverse free surfaceeffect on ship stability is minimized.

There are situations in the field of marine transportation whereinvolume utilization is of ultimate importance. It is therefore necessary,in many cases, to provide a container tank having maximum volumetricdimensions. FIG. -2 is illustrative of a tank having excellent volumecapabilities.

With reference now to FIG. 2, wherein like elements are similarlyreferenced, the second, third and fourth embodiments of the presentinvention are described. The ship is shown at M) and has an outer hulll2 and an inner hull 14. Again, the ship it) is provided with a concretetank 22 which is spaced from the inner hull M.

In the second embodiment of the present invention, the entire innersurface of the concrete tank 22 is provided with blocks of insulatingmaterial such as polyurethane blocks 46, and the inner surface of theseblocks 46 is covered by a liquid and gastight liner, such as apolyethylene liner 25. The space 34 is filled with dry sand. This secondembodiment of the present invention combines the advantage that sand isrelatively inexpensive with the advantage that polyurethane is anexcellent thermal insulator. It is contemplated that the respectivewidths of the sand layer and the polyurethane insulation system bedetermined by economic considerations. It should be evident that thisembodiment of the invention, as shown in FIG. 2, permits excellentutilization of the hold cubic and permits a large tank volume. Also, theconcrete tank is insulated from the cryogenic material.

The concrete tank of FIG. 2, due to'the fact that a portion of the sandsupport system has been removed, may be provided with a set ofconventional wooden foundation blocks 47. These blocks 47 serve totransmit the vertical loads caused by the cargo tank itself and thematerial which it houses to the bottom structure of the ship.

In the third embodiment of the present invention, it is contemplatedthat a system of insulating blocks 46 serves as the sole means forinsulating the cryogenic temperature as sociated with the transportedmaterial from the hull of the ship. The blocks 46, in this embodiment,entirely cover the inner wall of the tank 22. A liquid and gasimpervious liner 25 is also provided, this liner covering the innersurface of the insulating block system. It should be evident that thisembodiment provides for excellent use of the hold cubic and permits alarge tank volume. Also, the concrete tank is insulated from thecryogenic material. In this embodiment, it is necessary that foundationblocks 47 be provided.

There are numerous instances in which it is desirable to provide accessto the containment tank. In this manner, the tank is available forinspection, servicing and other operations. Consequently, the fourthembodiment of the present invention contemplates appending theinsulating blocks directly to the inboard side of the ships hull. Withinthis insulating block system is located the concrete tank of the presentinvention, the inner wall of this tank being lined with a liquid andgastight liner. Since in the fourth embodiment of this invention no sandis provided, it is necessary that there be provided conventionalfoundation blocks to support the tank.

As noted above, there is a fifth embodiment of the present invention,this embodiment being depicted in FIG. 3 and relating to a simplifiedship whose entire hull structure is of concrete. More particularly, andwith reference to FIG. 3, there is shown a vessel 48 having a hull 50made entirely of steel reinforced concrete. Within the reinforcedconcrete hull 50 is a polyurethane block insulation system 52. There isalso provided a gas and liquidtight liner 54 of polyethylene which formsa seal between the-polyurethane system 52 and the liquid within thehollow of the hull 50. This concept permits maximum utilization of theinternal cubic of a vessel and presents the most simplified constructionfor a system adapted to transport cryogenic fluids. Again, as in theembodiments shown in FIGS. 1 and 2, there are provided a series of side,bottom and upper wing ballast tanks for ballasting the ship during theunloaded leg of its voyage.

In view of the substantial quantities of materials to be transported andin view of the temperatures of these materials, it may be desirable toprestress the concrete tanks constructed in accordance with the presentinvention. This may be simply accomplished by preloading the reinforcingrods in tension during tank construction.

While the present invention has been described with particular referenceto the figures, it should be notedthat the above description is givenfor illustrative purposes only, and that it is the intent that thepresent invention not be limited thereto, but only be limited as setforth in the appended claims.

We claim:

1. A ship system adapted for the marine transportation of liquefied gasat substantially cryogenic temperature and atmospheric pressure, andincluding: a steel hull; at least one concrete tank permanently locatedwithin, spaced from, and capable of contracting and expandingindependent of said hull, said tank being for the containment ofliquefied gas; liquid and gas impervious liner means for physicallyisolating said liquefied gas from the hull of the ship; and insulationmeans for thermally isolating said liquefied gas from the hull of theship.

2. The invention as recited in claim ll, wherein the space between theconcrete tank and the hull of the ship is filled with dry sand.

3. The invention of claim 2, wherein said liquid and gas imperviousliner means isolates the liquefied gas from the inner wall of said tank.

4. The invention as set forth in claim 2, wherein said tank is shapedsuch that its upper region, relative to its lower region, is taperedabout its centerline.

S. The invention recited in claim 2, and further comprising means forlimiting the motion of said concrete tank within the hull of said ship.

6. The invention of claim 2, and further comprising means for positivelyheating the hull of said ship.

10. The invention recited in claim 9, wherein said insulation meansabuts the hull of said ship and wherein the liquid and gas imperviousliner abuts the inner wall of said concrete tank.

11. The invention recited in claim 1, wherein said ship is provided witha plurality of holds within its hull for housing a plurality of concretetanks.

12. The invention as recited in claim 1, wherein said insulatingmaterial is polyurethane and wherein said liquid and gas imperviousliner is polyethylene.

2. The invention as recited in claim 1, wherein the space between theconcrete tank and the hull of the ship is filled with dry sand.
 3. Theinvention of claim 2, wherein said liquid and gas impervious liner meansisolates the liquefied gas from the inner wall of said tank.
 4. Theinvention as set forth in claim 2, wherein said tank is shaped such thatits upper region, relative to its lower region, is tapered about itscenterline.
 5. The invention recited in claim 2, and further comprisingmeans for limiting the motion of said concrete tank within the hull ofsaid ship.
 6. The invention of claim 2, and further comprising means forpositively heating the hull of said ship.
 7. The invention as set forthin claim 3, wherein said insulation means is positioned intermediate theinner wall of said tank and the liquid and gas impervious liner.
 8. Theinvention recited in claim 7, wherein said insulation means abuts theinner wall of said tank and wherein the liquid and gas impervious linerabuts the inner surface of said insulating means.
 9. The invention asrecited in claim 2, wherein said insulation means is located in thespace between the concrete tank and the hull of the ship.
 10. Theinvention recited in claim 9, wherein said insulation means abuts thehull of said ship and wherein the liquid and gas impervious liner abutsthe inner wall of said concrete tank.
 11. The invention recited in claim1, wherein said ship is provided with a plurality of holds within itshull for housing a plurality of concrete tanks.
 12. The invention asrecited in claim 1, wherein said insulating material is polyurethane andwherein said liquid and gas impervious liner is polyethylene.